1. Field of the Invention
The present invention generally relates to mobile communication systems, and more particularly to a system and method for canceling noise in a mobile terminal.
2. Background of the Related Art
Generally speaking, there are two types of wireless systems: Code Division Multiple Access (CDMA)-based synchronous systems and Time Division Multiple Access (TDMA)-based asynchronous systems. The TDMA-based asynchronous system most widely used in Europe is the Global System for Mobile communications (GSM) system. GSM combines TDMA with a Frequency Division Multiple Access (FDMA) scheme. In a GSM mobile terminal, noise is generated from an audio output terminal due to a time burst ripple on a battery power line. This form of noise is called TDMA noise.
FIG. 1 shows a power unit of a mobile terminal. This unit is designed so that its audio power terminal is separately formed and one or more audio-exclusive Low Drop Output regulators (LDOs) are used to minimize influence of noise within an audio frequency range caused by ripple in a power terminal of an audio amplifier.
When operated in accordance with a related-art method, the FIG. 1 power unit merely focuses on minimizing TDMA noise after it has been created. This method does not prevent the generation of TDMA noise at its source. Also, because additional circuits such as the audio power terminal and audio-purpose power regulator are used, the related-art method does not promote miniaturization, which is the recent trend in mobile terminal design.